the present invention relates to novel uracil derivatives and herbicides having an selectivity and containing the uracil derivatives as active ingredients.
A large variety of herbicides have been prepared and practically used for protecting important crop plants such as rice, soybean, wheat, corn, cotton, beet, etc., from weeds and for enhancing productivity of these crop plant. The herbicides may be roughly classified into the following three types according to the locality of application: 1 herbicides for upland cropping, 2 herbicides for paddy field and 3 herbicides for non-arable land. Each kind of herbicides can be further classified into subclasses such as soil incorporation treatment type, pre-emergence treatment type and post-emergence treatment type (foilage treatment) according to the method of application.
With increase of global population in recent years, there is no denying the fact that productivity of principal crop plants gives a serious influence to food economy of each country, and thus enhancement of productivity of principal crop plants is now a matter of paramount importance. In fact, for the people engaged in farming, it is still more necessary to develop herbicides which are capable of economical and efficient killing or controlling of growth of weeds which do harm to cultivation of crop plants.
As such herbicides, there are demanded the ones which can meet the following requirements:
(1) Herbicidal effect is high with small amount of application. (It is necessary, especially from the viewpoint of environmental protection, to kill the weeds by application of as small as amount of herbicide as possible.) PA0 (2) Residual effect is appropriate. (Recently, the problem is pointed out that the chemicals retaining their effect in soil for a long time could give damage to the next crop plants. It is thus important that the chemicals keep an appropriate residual effect after application). PA0 (3) Weeds are killed quickly after application. (It is made possible to perform seeding and transplantation of the next crop plant in a short time after chemicals treatment.) PA0 (4) The number of times of herbicide treatment (application) required is small. (It is of much account for the farmers that the number of times of weed-controlling work be minimized.) PA0 (5) Weeds killed or controlled by one of herbicide is of wide range. (It is desirable that different weeds such as broad-leaved weeds, graminaceous weeds and perennial weeds can be killed or controlled by application of one of herbicides.) PA0 (6) The application method is diversified. (The herbicidal effect is intensified when it can be applied in various ways, such as soil treatment, foliage treatment, etc.) PA0 (7) No damage to crop plants is given. (In a cultivated field where both crop plants and weeds co-exist, it is desirable that weeds alone are killed selectively by a herbicide.)
Nevertheless, there is yet available no herbicide which can meet all of the above requirements.
It is known that certain compounds of uracil derivatives have a herbicidal activity. For instance, in the Pesticide Manual, 8th Ed., p. 89 (published by The British Crop Protection Council, 1987), Bromacil as one the herbicides having uracil skeleton is disclosed.
There are also known the following hetero-ring derivatives which can serve as active ingredient for herbicides:
(1) 3-Aryluracil-alkyl, alkenyl and alkinylenol ethers represented by the following general formula: ##STR1## wherein R.sup.1 represents C.sub.1-8 alkyl, C.sub.2-6 alkenyl, C.sub.2-6 alkynyl, C.sub.2-8 alkoxyalkyl or n ##STR2## R.sup.2 represents halogen or cyano, R.sup.3 represents hydrogen or halogen, R.sup.4 represents hydrogen, fluorine or C.sub.1-4 alkyl, R.sup.5 represents C.sub.1-4 alkyl or C.sub.1-4 haloalkyl, or R.sup.4 and R.sup.5 may combine to represent tri- or tetra-methylene (in which R.sup.6 and R.sup.7 represent independently C.sub.1-4 aklyl, and m is 1 or 2), and X is O, O--C(O), O--C(O)--O or C(O)--O (Japanese Patent Application Laid-Open (Kokai) No. 64-107967).
(2) Compounds represented by the following general formula: ##STR3## wherein R.sup.1 represents hydrogen, C.sub.1-4 alkyl, C.sub.1-4 haloalkyl, formyl or C.sub.2-6 alkanonyl, R.sup.2 represents ether or a residue containing (thio)carbonyloxy or sulfonyloxy, the residue being directly linked to benzene nucleus A through oxygen atom, R.sup.3 represents halogen or cyano, R.sup.4 represents hydrogen or halogen, R.sup.5 represents hydrogen, halogen or C.sub.1-4 alkyl, and R.sup.6 represents C.sub.1-4 alkyl or C.sub.1-4 haloalkyl, or R.sup.5 and R.sup.6 may be combined together to represent tri- or tetrametylene, and salts of the compounds of the said formula wherein R.sup.1 is hydrogen (Japanese Patent Application Laid-Open (Kokai) No. 63-41466).
(3) Compounds represented by the following formula: ##STR4## wherein R.sup.1 represents hydrogen, C.sub.1-4 alkyl, C.sub.2-4 alkenyl, C.sub.2-4 alkynyl, C.sub.2-6 alkoxyalkyl, formyl, C.sub.2-6 alkanoyl or C.sub.2-6 alkoxycarbonyl; R.sup.2 represents hydrogen, C.sub.1-6 alkyl, C.sub.2-4 alkenyl, C.sub.2-4 alkynyl or C.sub.2-6 alkoxyalkyl; R.sup.3 represents halogen or nitro; R.sup.4 represents hydrogen or halogen; R.sup.5 represents hydrogen, halogen, C.sub.1-4 alkyl, chloromethyl, bromomethyl, hydroxymethyl (C.sub.1-5 alkoxy)methyl, (C.sub.1-5 alkylthio)methyl, cyano, nitro or thiocyanato; R.sup.6 represents hydrogen, C.sub.1-4 alkyl or C.sub.1-4 fluoroalkyl, or R.sup.5 and R.sup.6 are combined to represent trior tetramethylene, in which one of the said methylene groups may be substituted with oxygen or sulfur, or these groups may be substituted with C.sub.1-3 alkyl; and X represents oxygen or sulfur, in which (i) when R.sup.5 is fluorine, R.sup.6 is C.sub.1-4 alkyl or C.sub.1-4 fluoroalkyl, and (ii) when R.sup.5 is cyano, R.sup.6 is hydrogen or C.sub.1-4 alkyl, and X is oxygen, and salts of the compounds of the said formula wherein R.sup.1 and/or R.sup.2 represent (s) hydrogen (Japanese Patent application Laid-Open (Kokai) No. 61-221178).
(4) Herbicidal compounds having the general formula: ##STR5## wherein X is hydrogen or hydroxy, R.sup.1 is hydrogen or halo and R.sup.2 is alkyl, cycloalkyl, phenyl, alkenyl, and substituted derivatives of the above (U.S. Pat. No. 3,981,715).
(5) Herbicidal compounds having the general formula: ##STR6## wherein X is hydrogen or hydroxy, R.sup.1 is hydrogen or halo and R.sup.2 is alkyl, cycloalkyl, phenyl, alkenyl, and substituted derivatives of the above (U.S. Pat. No. 3,869,457).
(6) Compounds of formula (I): ##STR7## wherein R.sup.1 represents hydrogen, C.sub.1-4 alkyl, C.sub.3-4 alkenyl, C.sub.3-4 alkynyl, C.sub.1-4 haloalkyl, R.sup.2 represents ##STR8## or, when R.sup.1 represents haloalkyl, hydrogen, C.sub.1-8 alkyl, C.sub.2-8 alkenyl, C.sub.2-8 alkynyl or C.sub.2-8 alkoxyalkyl, R.sup.3 represents halogen or cyano, R.sup.4 represents hydrogen or halogen and R.sup.5 represents hydrogen, fluorine or C.sub.1-4 haloalkyl, as well as their enol ethers and salts (WO 88/10254).
Keen request is heard for the presentation of a herbicide which can meet the above-mentioned requirements (1)-(7), namely a herbicide which shows selectivity in potency, with no fear of giving any damage to crop plants (crop injury), exhibits excellent herbicidal effect at low dosage against a vide variety of weeds, and is also capable of exhibiting desired effect in both soil treatment and foliage treatment.
As a result of the present inventor's further studies, it has been found that uracil derivatives having a methyl group at 1-position of the uracil ring, a trifluoromethyl group at 6-position thereof and a phenyl group at 3-position thereof which has a NHSO.sub.2 D.sup.26 group at 5-position of the benzene ring, a halogen atom at 4-position thereof and a hydrogen atom or a halogen atom at 2-position thereof, have a penetrative translocation activity and a high herbicidal activity at a very low dosage, and show, particularly, no phytotoxicity against soybean. Based on the finding, the present invention has been attained.